1. Field of the Invention
The present invention relates to a blower that includes a fan to draw air from an inlet and exhausts air through an outlet, and an electric apparatus that includes the blower.
2. Description of Related Art
For example, in the case of a notebook PC as an example of the electric apparatus, the amount of heat generated from a heat generating element such as a CPU increases as the performance of the notebook PC is improved. Therefore, it is likely that the configuration of a conventional heat dissipation device cannot dissipate heat sufficiently. Thus, a high-performance heat dissipation unit has been demanded. When the heat dissipation unit uses an air flow produced by a fan, the shape and arrangement of a heat dissipation fin, the interrelationship between the heat dissipation fin and a blowing fan (cooling fan), or the like have to be optimized.
Moreover, in the case of the electric apparatus for which compactness is critical such as the notebook PC, the arrangement of the blowing fan and the heat dissipation fin is limited strictly. Under these circumstances, e.g., JP 2000-082888 A discloses a heat dissipation device having a space-saving structure, as shown in FIG. 14.
In this heat dissipation device, heat is transferred from a heat generating element (not shown) located inside a metal case 21 to a heat dissipation fin 24 of a heat dissipation portion 23 by a heat pipe 22, and then dissipated by the air flow from a blowing fan 25. The heat dissipation portion 23 is located close to the blowing fan 25 and integrated with the metal case 21. An inlet 26 and an outlet 27 are provided in the side walls of the metal case 21. The inlet 26 and the outlet 27 are connected by a duct 28 via the blowing fan 25. The blowing fan 25 draws air from the inlet 26 to cool the heat dissipation portion 23 and then exhausts the air through the outlet 27.
With this configuration, the thermal conductivity of the case 21 made of metal is used effectively for the heat dissipation portion 23 of the heat dissipation device, and the blowing fan 25 is located close to the heat dissipation portion 23. Thus, the space saving can be achieved, and also the cooling efficiency can be improved. Moreover, since the inlet 26 and the outlet 27 are provided in the side walls that are at right angles to form a corner of the metal case 21, both air intake and air exhaust can be performed efficiently by the blowing fan 25, which is effective in improving the cooling efficiency.
However, in the heat dissipation device having the above configuration, JP 2000-082888 A merely discloses that the blowing fan is integrated with the heat dissipation portion, and does not particularly refer to the slit widths of the inlet and the outlet. The slit widths of the inlet, the outlet, and the heat dissipation fin need to be optimized not only to improve the cooling efficiency, but also to achieve the space saving in the heat dissipation unit that uses the air flow produced by the blowing fan.
Although the cooling performance of the heat dissipation unit may be improved by making the inlet and the outlet larger, there is the problem of dust entering easily. In particular, when the electric apparatus is used outdoors, rain, dust, dirt, or the like can enter the apparatus and make it difficult to operate the heat dissipation unit using the blowing fan. If dust enters the apparatus, the blowing fan or the heat dissipation fin becomes clogged or damaged, and proper heat dissipation likely cannot be performed.
Therefore, it is desirable that the inlet and the outlet have the largest possible size while taking into account the conditions required from the allowable size of dust, the slit width of the heat dissipation fin, or the like in view of the dust-proof performance of the blowing fan (i.e., the blowing fan is not substantially affected by dust).
The above problem is not limited to the heat dissipation unit that uses the heat dissipation fin for cooling in the notebook PC. The same problem also is present in a blower that includes a fan to draw air from an inlet and exhausts air through an outlet and in an electric apparatus that includes the blower.